Book/Dissertation / PhD Thesis FZJ-2021-05551

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Synthese von Cr$_{2}$AlC MAX-Phasen Kompositen und Bestimmung ihrer oxidativen Eigenschaften



2021
Forschungszentrum Jülich GmbH Zentralbibliothek Verlag Jülich
ISBN: 978-3-95806-598-7

Jülich : Forschungszentrum Jülich GmbH Zentralbibliothek Verlag, Schriften des Forschungszentrums Jülich. Reihe Energie & Umwelt / Energy & Environment 558, ii, 119 S. () = RWTH Aachen, Diss., 2021

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Abstract: Three different ceramic matrix composites (CMCs) were produced using Cr$_{2}$AlC as a matrix, and carbon, SiC, and Al$_{2}$O$_{3}$ short fibers as a secondary phase. Cr$_{2}$AlC powders were synthesized by solid-state reaction, followed by mixing with the fibers, and full densification using a field-assisted sintering technique (FAST/SPS). Carbon fibers react strongly with Cr$_{2}$AlC, meaning that these composites are not suitable for use, while the reaction of SiC fibers is less strong. The composites containing alumina fibers do not exhibit any reaction. Oxidation tests of the monolithic Cr$_{2}$AlC and the composites were performed by thermogravimetric analysis. Of all the chosen CMCs, 10 wt.% SiC fibers resulted in the lowest mass gain. The parabolic and cubic rates of oxidation were determined to find the best fitting calculation. The overall oxidation response is parabolic. The alumina layer formed at 1000 °C is well attached and the oxidation response is good. However, at 1200 °C, this layer detached for monolithic material and 10 wt.% Al$_{2}$O$_{3}$ fibers. In long-term oxidation tests at 1200 °C for 4 weeks, a strong reaction of the CMCs in contrast to the monolithic material is observed. The oxidation response of the alumina fiber CMC is good under realistic conditions using a burner rig for cyclic oxidation, as defects or degradation are barely visible, and the alumina layer is well attached. The mechanical reinforcement effect of the fibers was implemented by measuring the compressive streng that room temperature and 900 °C. This reinforcement is clearly evident here. CMCs with Al$_{2}$O$_{3}$-fibers with stand higher compressive stresses than monolithic material. The highest compressive stresses are measured in CMCs with SiC fibers, whereby the reason for this increase can also lie in the secondary phases that arise during sintering.


Note: RWTH Aachen, Diss., 2021

Contributing Institute(s):
  1. Werkstoffsynthese und Herstellungsverfahren (IEK-1)
Research Program(s):
  1. 899 - ohne Topic (POF4-899) (POF4-899)

Appears in the scientific report 2021
Database coverage:
Creative Commons Attribution CC BY 4.0 ; OpenAccess
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The record appears in these collections:
Document types > Theses > Ph.D. Theses
Institute Collections > IEK > IEK-1
Document types > Books > Books
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 Record created 2021-12-23, last modified 2022-01-31


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